UDP 30303
Synopsis
- Ethereum’s devp2p discovery protocol (discv4) uses UDP port 30303 by default; this is the standard for go-ethereum (Geth) nodes on mainnet and testnets like Sepolia and Goerli.
- Other Ethereum clients also use UDP 30303 for peer discovery, including OpenEthereum/Parity, Nethermind, and Hyperledger Besu.
- Ethereum Classic clients (e.g., Core-geth and Besu-ETC) listen on UDP 30303 for the same discovery mechanism.
- Enterprise and private Ethereum networks based on Geth (e.g., ConsenSys Quorum) typically use UDP 30303 for node discovery unless reconfigured.
- Because 30303 is the well-known Ethereum peer port, it is routinely scanned by attackers, and Ethereum nodes have been targets of DDoS and eclipse-attack attempts over the devp2p layer, so operators often rate-limit or firewall UDP/30303.
Observed activity
Last 30 days
Detailed chart